Based on this 45-45-90 triangle, the length of FD is equal to 6 units.
Based on Pythagorean theorem, the length of sides of a right-angled triangle are always in the ratio 1 : 1 : √2, which can be rewritten as follows;
x : x: x√2.
Where:
x represent the length of sides of a right-angled triangle.
Note:
DE is the opposite side.
FE is the adjacent side.
FD is the hypotenuse.
Based on the 45-45-90 triangle, the length of FD can be calculated as follows:
FD = FE × √2
FD = 3√2 × √2
FD = 3 × 2
FD = 6 units.